Note that there isn't any art for a grey belt in the D1 Leather set artwork, but I'm completely convinced that's due to a file name error and it should be Ceinture en peau de dragon tendue.Together the pieces look like this, so judge for yourself. Note that the leather and metal studs of the belt are identical to the "V" neck of the chestpiece and seem to have been designed to match.That belt is officially from the Gray colour of the "D2 Leather" set (e.g. it's supposed to belong with Crescent Moon Armor though it doesn't match at all), but matches this set much better. More compelling evidence is that there is a "D1" belt for the brown version of this set (Wanderer's Garb) and it's identical in style to these nominally "D2" belts.

There are four other colours of this artwork in the database and all are used by at least a few pieces. Only two have mostly-complete sets. The remaining two are only present in a few pieces, not enough to make proper sets from. See:

Note that I've included the matching belts from the "D2 Leather" set, as explained above. In the case of Green it doesn't seem to match the existing pieces that closely, but it would have made sense with a full set (it matches the neck of the chest).